THe oligo-isoadenylate synthetase (synthetase E) and protein kinase induced in mouse cells by treatment with interferon (IFN) will be identified by two-dimensional gel electrophoresis. The cells will be treated with IFN and the newly synthesized proteins labeled with radioactive amino acids. The enzymatic activities will be bound to poly(rI).poly(rC) agarose columns, eluted in high salt, precipitated, subjected to two-dimensional gel electrophoresis, and fluorographs prepared. This procedure will be used for L cells (which produce both enzymatic activities) and embryonal carcinoma cells (which produce only synthetase E). Comparison of the fluorographs will permit identification of the two activities with the displayed polypeptides. The kinetics of synthesis and final level of synthatase E, protein kinase and oligo-2-5A-dependent ribonuclease will be determined for normal and IFN-selected L cells (which are not growth inhibited by IFN) treated with various concentrations of IFN. The data obtained will be correlated to cell growth inhibition.